Sensitive altimeter



March 4, 1930. G. P. LUCKEY SENSITIVE ALTIMEIER Filed June 27, 1923 INVENTOR GeoroaPL a c/fig ATT NEY Patented -Mar. 4, 1930 i [UNITED STATES enonen r. LUCKEY, or DAYTON, onto snnsrrrvn ALTIMETER.

Application filed June 27,

This invention relates to altimeters and has particular reference to an altimeter of extreme sensitivity and range for aeronautical use. I

It is the prime object of this invention to provide an altimeter that will be rugged, compact, accurate and sensitive to the smallest change in altitude and which will be accurate over a great range of variation in altitude.

It is the further object to provide an instrument of this character, with a temperature compensating device which may be easily adjusted so as-to simultaneously vary the effective length-0f a lever arm in two series of transmitting systems connected to two separate aneroid capsules.

Further objects will be more fully set forth in the attached specification and. claims.

In the drawing:

Fig. 1 is a sectional elevation of an embodiment of my invention.

Fig. 2 is a top plan view, and 3 is a detail' of the link connections between the aneroid capsules.

4 Referring to the drawings, Fig. 2 is a bowlshaped housing having a glass or other transparent top 4 and carrying the operating mechanism including 'dials 6 and 8 with zero adjusting mechanism v10 for the former.

Within the bowl 2'and secured to the same is a skeleton-supporting disk 12 upon which two bellows or aneroid capsules 14 preferably of metal, are mounted, while supported from the disk 12 are yokes 16 and 18, upon which the levers, bearings and gear trains are mounted. To the inner ends of the capsules are rigidly secured in any, suitable man-' ner, projections 20, 22, pivoted to arcuate links 24 and 26 in turn pivotally connected with angularly adjustable arms 28, 30 guided by auxiliary arms 34 and 32,-which are pivoted together at 36 on a shaft 38. The shaft 38 is mounted in jewelled bearings and provides'a support for a counterbalanced segmental gear 40, positioning collars being provi'ded therefor on the shaft.' The segmental gear 40, meshes with a pinion 42, carried by a countershaft44, which in turn carries a gear 46, meshing with a pinion 48, carried by PATEN'Il OFFICE BEISSUED 1923. Serial No. 648,057.

a second countershaft 50. The counters hafts 44 and 50, are also mounted in jewelled bearings and carry at their outer ends pointers 52 and 54 respectively, which are arranged to move over the faces of dials 8 and 6. The gear ratio between the gears 46 and 48 is properly chosen so that the desired number of revolutions of the hand 54 for onerevolution of the hand 52 are obtained. The dials 6 and 8 are graduated in equal spaces, the first for example, being raduated for one thousand feet change in a titude per revolution, and the latter for any desired multiple of the one thousand feet change.

Referring more particularly to Fig. 3, the links and arms connecting the projections 20 and 22 to the shaft 38, are especially designed to change the motion of the aneroid capsules for equal changes in pressure, into a uniform circular motion by a proper proportion of the lengths of the various arms and links, the distance between the aneroid ends of these arms and the pivot 36, the lateral spacing of the links 24 and 26, and the distance be tween the point 36 and-the inner ends of the links 24-and 26. The non-uniform rectilinear motion of the capsules is changed into a uniform circular motion by this mechanism and the scales therefore contain equal graduations. This is absolutely necessary in an instrument inwhich two pointers are used wherein one pointer travels over the same scale a number of revolutions. If a square scale or other irregular scale was used, it would be impossible or at least extremely con fusing, to obtain the reading of the pointer.

The ends of ,the links 24 and 26 are attached to the point 36 through an adjustable linkage 28, 34. Calling the end of the link 24, a, the point 36, b, and the end of link 26, c, the distance a?) is an imaginary link connecting 24 to 36, the length of which may be varied manually if desired, in order to adjust the range of movement of the pointer. This may be necessary in case different aneroid capsules are used from those intended, or in case one is replaced in a finished instrument. By, this means also, it is possible to make the scales in quantities with the assurance that the instrument may be easily adjustedto accommodate itself to this scale.

' The arms or links 28 and 30, are attached together and to an adjusting screw 56. By adjusting this screw 56, lever arms ab and be,

are simultaneously lengthened or shortened increments of motion of the projections and 22 inward will produce equal arcuate increments of motion of the points a and 0 about axis 38. Since the-total angular movement of the line abc is only about 30 degrees, the proper location of the line ate in relation to the line of motion of the projections 20* and 22 may be chosen so that the shaft 38 is r0- tated through substantially equal angles as the pressure of the outside air varies equal amounts, and as the bellows 14: expands in decreasing amounts which vary, like a spring, about as the square root of the changes of air pressure.

In order that compensation may be made for temperature changes, two links such as the links 28 and 30, or the links 32 and 34, or the adjusting screw 56 of the toggle adjusting mechanism, may be made of the material or combination of materials of suit able coefiicients of thermal expansion. With sucha construction the arms a?) and be may 1 be automatically varied in a suitable manner by a temperature change of the atmosphere or of the instrument and which will correct errors introduced .by the expansion of parts of the mechanism.

What I claims is:

1. In an instrument having sealed atmosphericpressure responsive means, a'plurality of dials, an .indicator for each of said dials, one of said dials and indicators being geared to the other so as to move only a fraction of arevolution for each complete revolution of the other, link mechanism connecting said pressure responsive means to said indicators for-transforming unequal movements of said means into uniform rotary movement of said indicators, and a device included in said mechanism for changing the ratio of the movement of the said indicators in respect to means.

2. In an instrument having atmospheric 4 .a revolution for each'complete revolution of the larger indicator, and a system of pivotally connected links connecting said indicators to said pressure responsive means for translows to said pointer, and a unitary adjust-I ing means for said link means to simultaneously and equally vary'the ratio of the movement of each of said bellows to the movement of the pointer.

In testimony whereof I aifix my signature.

' GEORGE P. LUCKEY.

the movement of said pressure responsive forming unequal movements of said vpres- 

